It is common for fastening elements such as bolts and nuts to be fastened to one another, or to hold down one material to another. A bolt may have an external helical thread and a nut may have an internal helical thread. The internal thread and the external thread may be configured to allow the nut and bolt to axially move relative to one another by torqueing one of the members relative to the other. Upon tightening, the axial force between the nut and bolt is resisted by the threads. As such, one or more materials may be sandwiched between a head of the bolt and the nut to tighten the nut and the bolt around the one or more materials.
However, common fastening elements may loosen after being tightened. For example, thread profiles may be manufactured according to a certain tolerance, causing a tightened nut and bolt to loosen.
U.S. Pat. No. 8,671,547 issued to Matsubayashi et al. discloses a fastening member that supposedly exerts a loosening-inhibition effect. However, Matsubayashi et al. is focused on elastic deformation of a thread, and is therefore limited in providing a loosening resistance, since an elastic deformation of the thread would naturally be forced back to an original undeformed state, which would cause or allow loosening axial forces.
Further, Matsubayashi et al. is focused on elastically deforming an external thread to directly increase a frictional force between an internal flank of a nut and a pressure-side flank of an external thread, due to the elastic deformation. For example, an axial force resulting from a tightening torque applied to the screw of Matsubayashi et al. will be opposed and resisted by the elastic deformation. As such the hypothetical loosening-inhibition effect of Matsubayashi et al. is caused by a loosening axial force directed away and opposite from a tightening axial force direction.
The fastening arrangement proposed by Matsubayashi et al. is limited and problematic in tightening two or more fastening members together, since the elastic deformation causes a loosening axial force (e.g. away from a head of a bolt), opposing any fastening axial forces (e.g. toward a head of a bolt) which is normally required to tighten two objects together. For example, two pieces of material such as metal are commonly tightened together by sandwiching the two materials between a head of a bolt or screw, and a nut, and the elastic deformation of Matsubayashi et al. would resist tightening axial forces, thus defeating the purpose of fastening arrangements of bolts or screws and nuts.
As such, there exists a need for a fastening thread for effectively increasing a loosening resistance of a threaded fastening arrangement.